1. Mechanism of action of Delta 8- and Delta 9-tetrahydrocannabinol (THC) from marihuana. 2. Analgesic properties of the THC's and their metabolites. 3. Analgesic and other properties of synthetic cannabinoid- like compounds. 4. Interaction of opiate analgesics and prostaglandins in the quinea pig ileum. 5. Structure determination, receptor binding, and biological activity of halomorphides. 6. Analgesic properties of some terpenoid compounds. 9-Nor-9 Beta-hydroxyhexahydrocannabinol (9 Beta-OH-HHC) was synthesized and found to have morphine-like potency in the hot-plate, Nilsen, writhing, tail-flick, and bradykinin tests for analgesia. In single dose suppression of morphine abstinance tests in monkeys, 9 Beta- OH-HHC failed to substitute for morphine. In addition, it has now been found to have anticonvulsant and hypotensive properties in mice and dogs, respectively. Several other 9-hydroxy cannabinoid-like compounds have been prepared. None had potent analgesic properties, but all had potent CNS depressant properties. Thujone, a small terpenoid molecule, has been found to have analgesic potency in the hot-plate test equivalent to Delta 8- and Delta 9-THC, the active components of marihuana.